Pulverizing apparatus



F. l. RAYMOND.

PULVERIZING APPARATUS.

APPLICATION FILED AUG. 16, 1920.

Patented Nov. 7, 1922,

2 SHEETSSHEET l- F. I. RAYMOND.

PULVERIZING APPARATUS.

APPLICATION FILED Aue.1e.|92o.'

Patented Nov. 7, 1922.

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2 SHEETS-SHEET 2.

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.- UNITED: STA TIE'IS? 1PA. I 'ENI" a ine.

FRED I. RAYMOND, OF'EVANSTON,ILLINOIS, 'ASSIGNOR TO RAYMON JD BROTHERS IMPACT PULVEBIZER, COMPANY, OF ILLINOIS,

CHICAGO, ILLIN 01S, CORPORATION OF JPULVERIZING APPARATUS.

Application filed August 16,1920, Serial No. 403,756.

To all whom it may concern Be itknown that T, FRED T. citizen of the United States, residin Evanston, in the county of Cook .and tate of Illinois, have invented certain new and useful Improvements in Pulverizing Apparatus, of which the following is a specification.

My invention relates to pulverizing apparatus and more particularly to the type of apparatus in which the pulverized material is withdrawn from the pulverizer or grinding mill by a current of air, separated and the coarser material returned forfurther pulverization.

Tn pulverizing apparatus of this type, a current of air is passed" through thepulverizer casing and the material which is Suficiently fine to be capable of suspension in RAYMOND, a

the current of air is thus withdrawn from I the pulverizer. The material is then passed into a separator capable of efiecting, a separation of the finer particles of material from those which are not sufliciently fine, and which maybe called tailings. 'The coarser particles or tailings are then returned to the ulverizer'for further pulverization. It has iieen' customary to introduce the tailingsinto the pulverizerat a point where they must travel against the outgoing current of air to reach the pul'verizing mechanism. The result has been that a large percentage of the tailings are carried off again in the current of air without reaching -the pulverizing mechanism. This greatly reduces the efficiency of the pulverizer because eventually the air current becomes burdened with a large percentage ofmaterial which is fine enough to be suspended in the air and yet not sufiiciently fine to be removed by the separator as the finer product. v

The object of the present invent1on 1s to provide certain novel and improved constructions in pulverizing-apparatus whereby the coarser particles of material are efi'ec'-- tively repulverized and the eflicienclyfor capacity of pulverizing apparatus of t 1s type is increased.

.The invention'i s illustrated in a certain preferred embodiment in the accompanying drawings in which; I

Fig.1 is an elevation of a pul'verlzlng apparatus to which my invention has been applied.

Fig. 2 is an elevation partly in section of the pulverlzer and separator- 1g. 3 is an elevation of the pulverizer and separator of Fig. 2 taken from the right hand of the structure as shown in Fig. 2, and having a portion of the outer casing broken away. Q I

Like characters of reference desi nate like parts in the several figures of the rawings.

In Fig. 1 of the drawings T have illustrated a pulverizing apparatus of a well known type which comprises in general a pulverlzer 10; a separator 11, a fan or blower 12, a cyclone collector 13 and a collecting bin 14. The pulverizer is supplied with crushed material from the feed bin 15 through a feed spout 16 and a feeding mechanism 17, the particular construction of which forms no part of this invention.

casing 18 and comprises. an outer shell 24,

and an inner shell or cone 25, the space between the outer and inner shells communicating with' the pulverizer' casing.

The fan or blower 12 is supported in a convenient position above the top of the separator by a platform 26 on supports 27 and The pulverizer 10 is of a well known typeconnected on its intake or suction side with v the inner shell 25 of the separator by means of the pipe 28. The pressure side of the fan 12 is connected with the cyclone collector 13 by the pipe 29.

h The .air outlet of the cyclone collector is connectedwith the pulverizing mill casing by meansof a pipe or conduit 30, for the purpose hereinafter noted.

The pipe-30 terminates at 3lat apoint in close proximity to the blades of the revolvfing beater 20. :The lower part of the inner shell 25 is connected with the terminal of the pipe 30 by means of a conduit 32 in which is positioned a rotary valve 33 adapted to permit the passage of material from the cone 25 into the conduit 32 and yet at the same time preventing the passage of a current of air through the conduit. v

Operation: The apparatus operates as follows:

The material to be pulverized is fed into the pulverizer casing above the rotary beater by means of a Suitable feeding device which may be adjusted to feed the material at any desired rate. The material falls by gravity onto the grinding element which in the form of apparatus illustrated is a rotary beater revolving in a clockwise direction as indicated by the arrow in Fig. 2.

The suction fan 12 induces a rising current of air as indicated by the arrows in Fig. 2 through the pulverizer casing 18 and the space between thev outer and inner shells 2a and 25 and through the openings 3% in the upper part of the inner cone 25 and directed in a tangential path so as to set up a whirling motion. After the material has been pulverized sufiiciently fine to be suspended in the rising current of air it is carried into the separator and there a separation is effected between the particles of product which have been pulverized sufficiently fine and those which have not been pulverized sufiiciently fine. The coarser particles or tailings are permitted to fall to the bottom of the inner cone 25. The general construction and operation of the separator is illustrated in the patent to Pool 870,383 and accordingly need not be further described inasmuch as its specific construction forms no part of this invention.

The finer particles of product are carried out of the separator 11 through the pipe 28 the blower 12, and the pipe 29 and are introduced tangentially into the cyclone col-' lector 13 where the solid particles are separated from the air, and the former permitted to collect in the bin 14. Inasmuch as the cyclone collector is not 100 per cent efiicient the outgoing air from the cyclone collector usually carries a certain percentage of fine particles suspended therein. It is accordingly customary to return such air to the pulverizer casing in order both to save the product and to prevent the escape of the dust into the atmosphere. This air issues into the casing 18 at a point sufficiently close to the rotary beater 20 so as to be drawn through the beater before it again ascends through the casing. A valve 35 is provided for controlling circulation of the air. The system is closed except for the opening throughthe pipe 36 which is located at a point where the pressure in the system is substantially atmospheric and which serves to balance the system and permit the escape of excess air from the system. If desired a bag collector is placed over the end of the pipe 36 so as to prevent the escape of dust into the air.

The coarser particles of material collected in the cone 25 which. are not sufliciently fine by the pulley 37 permits the escape of these particles from the inner cone 25 without permitting any current of air to be set up through the cone 25 and the conduit 32 by the suction of the blower.

In former pulverizing apparatus of this type it is customary to permit the coarser particles to fall into the pulverizer casing from the bottom of the cone 25 as illustrated in the Poole patent. A. large percentage of such coarser particles never reach the pulverizing element because they have already been pulverized sufficiently fine to be suspended in the rising current of air and accordingly are carried out of the pulverizer with the current of air passing between the outer and inner shells 24s and 25.

With the present construction the coarser particles are returned directly to the pnl verizing element out of contact with the rising current of air and are drawn into the pulverizing element along with the return air from the pipe 30.

It should be noted that my invention is limited to a specific construction of pulveriz er or to a separator which operates by the action of centrifugal force as in the separator illustrated. It is applicable to pulverizing apparatus in which the pulverized material is withdrawn by a current of air and an accurate separation of the material so withdrawn effected between the finer product and the coarser product.

In the claims the term air is employed to designate the medium carrying the pulverized material in suspension but it will be understood that this term is used merely for the sake of brevity instead of the more generic term gaseous medium or its equivalent.

I claim:

1. A pulverizing apparatus comprising a casing, a pulverizin element in said casing, a separator, a fan or drawing a stream of .air and pulverized material from said casing through said separator, a conduit leading from said separator towards said pulverizing element and located within the suctional influence of said fan, and means in said conduit adap-tedto permit the coarser.

material to pass from the separator to the pulverizing element but adapted to prevent passage of a current of air in the reverse direction through the conduit. I

2. In pulverlzing apparatus, the combination of a pulverizer comprising acasing having a pulverizing element therein, a separator associated with said pulverizer and COIIIPI'ISIIIO" an outer cone and an lnner cone, a suction tan connected with said mner cone and adapted to induce a current of air from paths, said separator being adapted to effect a separation between the fine and the coarse material, a collector connected with 10 said separator for collecting the fine material, and a conduit connected with said inner cone provided with means for returning the coarse material to said pulverizing element out of contact with said induced cuir- 15 rent of air.

FRED RAYMOND, 

